In the last article we’ve discussed the particulars of voxel data definition and storage for voxel terrain we use at Roblox. From there on a lot of other systems read & write data from the storage and interpret it in different ways - the implementation for each system (rendering, networking, physics) is completely separate and not tied too much to decisions storage or other systems are making, so we can study them independently.

While logically speaking it would make sense to look at mesher next (which is how we call the component that is capable of taking a box of voxel data and producing triangle data representing the terrain surface with material attributes), since it is used by both physics and rendering systems, the algorithm is pretty involved and has quite a bit of “magic” so we will leave that for some other time and will instead look at physics today.

I have been working a lot on vertex cache optimization lately, exploring several algorithms from multiple axes - optimization performance, optimization efficiency, corner cases and the like. While doing so, I’ve implemented a program to verify that the algorithms actually produce results beneficial for real hardware - and today we will discuss one such algorithm, namely “Optimal Grid Rendering”.

It’s been about almost two years since we shipped the first version of smooth voxel terrain at Roblox, and with it being live for a while and seeing a lot of incremental improvements I wanted to write about the internals of the technology - this feature required implementing serialization, network replication, collision detection, ray casting, rendering and in-memory storage support and within each area some implementation details ended up being quite interesting. Today we’ll talk about voxel definition and storage.

We have successfully shipped the Metal rendering backend to millions of users, and I want to write a bit about that. There are varying opinions on Metal in the industry - some claim Metal would not have been needed if only Apple dedicated more attention to OpenGL and Vulkan, some say it’s the easiest graphics API that ever existed. Why even bother with Metal, some ask, if you can just write OpenGL or Vulkan code, and use MoltenGL or MoltenVK to the same effect? Here are my thoughts on the API.